Both IFFY (I’ll Find Files for You) and EFF (Empty Folder Finder) are available for download!
IFFY can help you find misplaced files by performing searches based on answers to simple questions. There are also advanced filters for narrowing your search.
EFF searches for empty folders, typically left behind by software uninstalls, so you can remove them. It’s mainly for picky people like me who like to keep their file system extremely tidy. There are also options for finding nearly-empty folders.
Check ’em out!